Rishi: Traditional Aśvamedha-anukramaṇī attribution (often treated as ritual/anonymous rather than a single ṛṣi); later tradition associates the Vājasaneyin corpus with Yājñavalkya
Devata: Aśva (sacrificial horse) identified with Yama/Āditya/Trita; ultimately Prajāpati/Āditya-bandhu
Chandas: Triṣṭubh (predominant cadence; mixed/irregularities possible in transmitted accent-text)
ási yámo asyā́dityo arván asi tritó guhyéna vraténa | ási sómena samáyā vípṛkta āhús te trī́ṇi diví bándhanāni
Translation
Thou art Yama; thou art the Āditya; thou, O Steed, art Trita by the hidden ordinance. Thou art, with Soma, in the appointed season set apart: they say of thee, ‘three are thy bonds in heaven.’